A strain of herpes is killing Pacific oysters

A deadly herpes virus called Ostreid herpesvirus 1 (OsHV-1) is infecting the Pacific oyster population and threatening to spread across the world, according to Smithsonian magazine. This type of oyster — native to the Pacific coast of Asia — is the world’s most popular and valuable species.

The strain is lethal for Pacific oysters, but don’t worry too much. A person who eats a herpes-infected oyster will not catch the virus, even if it’s eaten raw. But other bivalves like clams, mussels and scallops are all at risk for contracting it.

The Pacific oyster has become an introduced species to other parts of the world and is prolific in areas like France, the U.S. and Australia. They’re the number one species of oyster grown on America’s West Coast. In 2008, a microvariant of OsHV-1 was found in France and it killed 80 to 100% of the oyster beds affected by it.

Another outbreak in England in 2010 killed more than 8 million oysters. And it’s been detected in Tomales Bay, Calif. recently.

“Given the spread of the OsHV-1 microvariants elsewhere around the world, it may only be a matter of time until they reach U.S. coastal bays,” Colleen Burge, a professor of marine and environmental technology at the University of Maryland, wrote for The Conversation.

“Given the spread of the OsHV-1 microvariants elsewhere around the world, it may only be a matter of time until they reach U.S. coastal bays.”

(GaryIanReich/Getty Images/iStockphoto)

“Once OsHV-1 is established within a bay, mass oyster deaths typically occur each year during the summer when water temperatures are warm,” Burge, who worked with the NOAA Sea Grant aquaculture program on the oyster virus, wrote. “The situation is analogous to a human who is infected with herpes and periodically (gets) cold sores. Normally the virus is latent (present at a low level) and does not cause cold sores. But after a stressful situation, the virus replicates and cold sores emerge.”

Burge also said that not all of the oysters infected with the OsHV-1 strain of herpes will die. If the virus acts like other strains of herpes, it may inhabit an oyster but not affect it, lying latent until the bivalve is under stress, just like in humans. There’s no vaccination for oyster herpes and even if there were, it’s currently not permitted to use in the U.S.

Researchers are attempting to develop a herpes-resistant breed of oyster by using the OsHV-1 strain of the virus itself, much like how humans create vaccines.

“I am currently working with two strains of OsHV-1 — the California virus and a microvariant in France — to determine OsHV-1 resistance genes,” Burge wrote. “The most effective way to limit damage in new locations from OsHV-1 is to limit its spread. However, we also want to be ready in case OsHV-1 microvariants spread to the United States.”